Transcript for Jessica Ridgeway Case: 17-Year-Old Student Turns Himself In

serious news and a shocking update in the death of 10-year-old jessica ridgeway. Police arrested a 17-year-old. Austin reed sigg is set to mak his first court appearance today. Abc's clayton sandell has the story. Reporter: Investigators overnight scoured the westminster, colorado, home where austin sigg lives with his mother. Fbi agents combed the backyard for clues. Police towed away his car. I believe we have taken a significant step towards justice for jessica. Reporter: Sources tell abc news that sigg confessed the crime to his mother, who called police so her son could turn himself in. Austin has known the suspect since elementary school. He was -- never thought he would go this far. Reporter: Sigg is a community college student where classmates say he was studying mortuary science. In high school, he took part in a competition involving crime scene investigations, or csi. It's not uncommon for people who abduct women to be fascinated by crime and crime detection. Reporter: Jessica vanished october 5th on her walk to school. Her body was found a few days later. Sigg lives less than a mile from her home, about a half-mile from her school and close to this reservoir. That's where he allegedly attacked a female jogger in may, covering her face with a rag that smelled like chemicals. Authorities are also looking at this youtube video that briefly shows a boy that looks like sigg, wearing a small cross. It appears to be similar to one that police say was found at the crime scene. I never put two and two together. Reporter: With the suspect now under arrest, people in jessica ridgeway's community hope their nightmare is over. It's terrifying. I don't know why somebody could do this to somebody else. Reporter: Later this morning, sigg will be in court for his initial appearance, facing charges of kidnapping and murder. The judge says he will charge the 17-year-old as an adult. As a juvenile, he will not be eligible for the death penalty.

This transcript has been automatically generated and may not be 100% accurate.